The surface structure of the sample can be observed by irradiating electrons to the sample and detecting the secondary charged particles emitted from the sample while scanning. It is called a scanning electron microscope (hereinafter abbreviated as SEM). On the other hand, the surface structure of the sample can also be observed by irradiating an ion beam to the sample and detecting the secondary charged particles emitted from the sample while scanning. It is called a scanning ion microscope (hereinafter abbreviated as SIM). Especially, it becomes suitable to observe the sample by irradiating ion species with light mass, such as hydrogen or helium, to the sample, so that a sputtering operation becomes relatively small. Here, a secondary electron excitation region due to the penetration of hydrogen or helium ions into the sample surface is localized depending on the sample surface in comparison with electron irradiation, so that a SIM image using hydrogen or helium ions becomes very sensitive to sample surface information more than the SEM image. In addition, since the ion is heavier than the electron in the viewpoint of a microscope, it has characteristics that a diffraction effect can be disregarded in view of the beam focusing and an image with very large depth of focus is obtained.
And, when an electron or ion beam is irradiated to the sample and the electrons or ions transmitted through the sample are detected, information reflecting the sample interior structure can also be obtained. It is called a transmission electron microscope or a transmission ion microscope. Especially, when ion species having light mass such as hydrogen or helium is irradiated to the sample, its ratio transmitting through the sample increases, so that it is suitable for observation.
The gas field ionization ion source is expected to provide a fine beam because the energy with of an ion is narrow and an ion generation source size is small, and it is an ion source suitable for the above-described scanning ion microscope and transmission ion microscope. Japanese Patent Application Laid-Open No. S58-85242 (PATENT LITERATURE 1) discloses that when an emitter tip which has a minute projection formed at its end in a gas field ionization ion source is used, ion source characteristics become good.
“H.-S. Kuo, I.-S. Hwang, T.-Y. Fu, J.-Y. Wu, C.-C. Chang, and T. T. Tsong, Nano Letters 4 (2004) 2379 (NON PATENT LITERATURE 1)” discloses that the minute projection at the emitter tip end is produced by using a second metal different from the emitter tip material. An ion source with high luminance is realized by producing an atom nanopyramid structure at the emitter tip end.
“J. Morgan, J. Nolte, R. Hill, and B. Ward, Microscopy Today, Jul. 14 (2006) 24 (NON PATENT LITERATURE 2)” discloses a scanning ion microscope provided with a gas field ionization ion source which emits helium ions.
Japanese Patent Application Laid-Open No. H03-74454 (PATENT LITERATURE 2) discloses a mechanism that an ionizing chamber is provided with bellows in a gas field ionization ion source. But, the ionizing chamber is in contact with room temperature through a vacuum sample chamber wall, and it is not indicated that the gas supplied into the ionizing chamber has a problem of striking the high-temperature vacuum sample chamber wall. And, it is not described either that the emitter tip is tilted.
Japanese Patent Application Laid-Open No. S62-114226 (PATENT LITERATURE 3) discloses a direction regulating mechanism in a gas field ionization ion source that enables to change the axial direction of the ion source. But, an ionizing chamber is in contact with room temperature through a vacuum sample chamber wall, and it is not suggested that the gas supplied into the ionizing chamber has a problem that it strikes the high-temperature vacuum sample chamber wall. And, an extraction electrode tilts with a change in the axial direction of the ion source.
Japanese Patent Application Laid-Open No. H01-221847 (PATENT LITERATURE 4) discloses a selector switch to connect a high voltage introduction line for an extraction electrode to a high voltage introduction line for an emitter tip, and also discloses a gas field ionization ion source capable of preventing an electric discharge between the emitter tip and the extraction electrode after a forced electric discharge treatment between an ion source outer wall and the emitter tip, namely a so-called conditioning treatment.
Japanese Patent Application Laid-Open No. H08-203461 (PATENT LITERATURE 5) discloses a structure of a charged beam apparatus that a vibration preventing tool is provided between an apparatus stand and a base plate on which a charged particle apparatus main body is mounted. But, there is no description about a cooling mechanism of a charged particle source.
The sample can also be minutely processed by emitting the ion beam to the sample. This processing applies an action that the particles constituting the sample are emitted from the sample by an ion sputtering operation. For this processing, a focused ion beam (hereinafter called as FIB) using a liquid metal ion source (hereinafter called as LMIS) is suitable. And, an FIB-SEM apparatus, which is a composite machine of the SEM and the focused ion beam, is also used in recent years. This FIB-SEM apparatus can perform SEM observation of a cross section of a square hole formed at a desired position by emitting the FIB.
For example, Japanese Patent Application Laid-Open No. 2002-150990 (PATENT LITERATURE 6) discloses a device for observing a defect, a foreign matter or the like and analyzing by forming an angle hole near an abnormal portion of a sample by the FIB, and observing a cross section of the angle hole by the SEM device.
PCT International Publication WO99/05506 (PATENT LITERATURE 7) discloses a technology that an FIB and a probe are used to take a minute sample from a bulk sample so to observe through a transmission electron microscope.
Japanese Patent Application Laid-Open No. H09-312210 (PATENT LITERATURE 8) discloses a cooling technology that a to-be-cooled body of a super-conductive magnet and a refrigerator are separated from each other, and they are thermally connected by means of a detachable vacuum insulated pipe. But, it does not disclose a structure to prevent the operation vibration of the refrigerator when they are mounted and the cooling operation is performed.
Japanese Patent Application Laid-Open No. H04-230880 (PATENT LITERATURE 9) discloses a structure that a high frequency receiving coil for NMR is determined as a to-be-cooled body, and the to-be-cooled body is thermally connected to a cooling stage, which is cooled with a refrigerant, in a vacuum space. But, it does not disclose a structure that the vacuum space having the to-be-cooled body therein and the vacuum space having the cooling stage are hermetically isolated by a bulkhead from each other.